Brass jugs polish off disease

April 8, 2005By Roxanne KhamsiThis article courtesy of Nature News.

Developing world urged to ditch plastic for traditional pitchers.

Brass water containers could combat many water-borne diseases, according to microbiologists. The discovery suggests that these vessels should be used in developing countries, where people typically view cheaper plastic containers as the better option.

Water-borne diseases remain a serious threat in many poor regions of the world, with around 2 million children dying each year from diarrhoea. Efforts to provide safe drinking water have had difficulty reaching remote areas.

Even in places with basic water-purification systems, people often opt for riskier wells under trees because the water is cooler, says Rob Reed, who led the brass study. On a recent trip to India, Reed, a microbiologist at Northumbria University in Newcastle upon Tyne, UK, witnessed villagers doing exactly this.

But he also heard an interesting piece of local wisdom: people believe that traditional brass water containers offer some protection against sickness. The idea intrigued Reed, who was in Asia investigating the antibacterial effects of sunlight on water.

He has now found that bacteria are indeed less likely to thrive in brass water pots than in earthenware or plastic ones. "It's one of the traditional ideas of water treatment and we were able to find a microbiological basis for it," he says.

Hold that thought

Reed, with his colleagues Puja Tandon and Sanjay Chhibber, carried out two series of experiments. In Britain, the researchers filled brass and earthenware vessels with a diluted culture of Escherichia coli bacteria, which can cause illnesses such as dysentery. They then counted the surviving bacteria after 6, 24 and 48 hours. A similar test was carried out in India using naturally contaminated water.

The amount of live E. coli in the brass vessels dropped dramatically over time, and after 48 hours they fell to undetectable levels, Reed told the Society for General Microbiology's meeting this week in Edinburgh, UK.

The key to the result is copper, which can disrupt biological systems, Reed explains. The element acts by interfering with the membranes and enzymes of cells; for bacteria, this can mean death. Pots made of brass, an alloy of copper and zinc, shed copper particles into the water they contain.

The amounts that circulate into the brass water vessels would not harm humans, Reed adds. According to the researchers, even a person drinking 10 litres of such water in a single day would take in less than the daily recommended dose of copper or zinc.

Plastic beliefs

Brass water pots also easily outperformed plastic ones, the researchers discovered. Plastic, says Reed, did not inactivate the bacteria. But many people in developing nations use plastic drinking vessels, because they view them as more modern.

Other factors also influence their choice. "Brass is an order of magnitude more expensive. People are switching to plastic because it's cheaper," Reed explains. He hopes that the disease-fighting properties of brass containers will convince people to switch back to traditional ware. "They work at the individual household level, so you don't need a great deal of infrastructure" unlike other safe-water systems, Reed says.

Although Reed declines to speculate about exactly how many lives could be saved by switching to brass, he points to the millions of lives claimed each year by water-borne diseases. Storing water in brass for two days could stop this, he suggests: "The potential is great."